Solar-like oscillations in distant stars as seen by CoRoT : the special case of HD 42618, a solar sister

We report the observations of a main-sequence star, HD 42618 (Teff = 5765 K, G3V) by the space telescope CoRoT. This is the closest star to the Sun ever observed by CoRoT in term of its fundamental parameters. Using a preliminary version of CoRoT light curves of HD 42618, p modes are detected around 3.2 mHz associated to l = 0, 1 and 2 modes with a large spacing of 142 μHz. Various methods are then used to derive the mass and radius of this star (scaling relations from solar values as well as comparison between theoretical and observationnal frequencies) giving values in the range of (0.80 − 1.02)Msun and (0.91 − 1.01)Rsun. A preliminary analysis of l = 0 and 1 modes allows us also to study the amount of penetrative convection at the base of the convective envelope.